[BUG] Modbus TCP fails to reconnect automatically

[Tpro4391]

Describe the bug

1. Configure modbus tcp to PLC, read register value ok
2. Turn off PLC (simulate connection loss)
3. Turn on PLC again (connect back)
4. Check ioT Gateway reports connection error, cannot reconnect:
   to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:13 tb-gateway-scada | 2024-11-11 03:59:13 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:15 tb-gateway-scada | 2024-11-11 03:59:15 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:17 tb-gateway-scada | 2024-11-11 03:59:17 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:19 tb-gateway-scada | 2024-11-11 03:59:19 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:21 tb-gateway-scada | 2024-11-11 03:59:21 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:23 tb-gateway-scada | 2024-11-11 03:59:23 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:25 tb-gateway-scada | 2024-11-11 03:59:25 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused
   2024-11-11 10:59:27 tb-gateway-scada | 2024-11-11 03:59:27 - |ERROR| - [tcp.py] - tcp - connect - 187 - Connection to (192.168.31.240, 502) failed: [Errno 111] Connection refused

Connector name (If bug in the some connector):
Modbus TCP

Error traceback (If available):

'deviceName'
Traceback (most recent call last):
  File "<input>", line 2, in <module>
KeyError: 'deviceName'

Versions (please complete the following information):

• OS: Docker Windows
• Thingsboard IoT Gateway version 3.6
• Python version[e.g. 3.7]

[imbeacon]

Hi @Tpro4391,

Thank you for your interest in ThingsBoard IoT Gateway.
The gateway contains parameter waitAfterFailedAttemptsMs, for Modbus connector, it means that the gateway will recreate a connection, only after this amount of time, when all retries of connection to current master were failed, in current version of the gateway, it cannot be less than 5 minutes, and it will retry to connect in 5 minutes, we will change this limit to 30 seconds in 3.7 version.